But if photons are not particles, how can we explain the particlelike impact points? Here’s how: Each photon is a spread-out wave, an extended bundle of field energy that comes through both slits and then fills the screen just before interacting with it. Each photon then interacts with the entire screen. But the screen is made of zillions of individual atoms. Because a photon cannot be subdivided, it must deposit its entire energy into just one of these atoms “chosen” randomly (Chapter 6). This atomic-level interaction is then amplified so that a tiny visible flash appears on the screen.
